Disc brakes of the above type are known, for example, from DE 103 56 801 B3. The first sealing device is formed by an elastic protective cap that has the form of a bellows-type sleeve that extends as a result of screwing out a pressure spindle of the adjusting device. In the known disc brake, it represents the only device for sealing the annular space and thus the interior of the brake caliper and the brake application and adjusting components it contains from external influences of any kind. The sealing device itself is exposed to the most varied external influences. These include mechanical influences such as gravel impact or inappropriate handling when servicing the brake. There are also thermal influences since the brake pad and brake disc are in the immediate vicinity. These influences can damage or even destroy the bellows-type sleeve. If the bellows-type sleeve is damaged and destroyed, however, all brake components will be exposed to environmental influences without protection so that the brake function may be impaired or even fail completely.
It is the problem of this invention to improve the disc brake according to DE 103 56 801 B3 in such a way that the brake interior and the components housed in it are effectively protected and that both the first installation of the brake and any later replacement of components are simple.
According to the invention, this problem is solved in a disc brake of the type described above by a holding device that holds a second sealing device for sealing the annular space at least partially. Furthermore, a third sealing device is provided that bears against the holding device for sealing the annular space at least partially.
Providing a second sealing device makes the entire sealing system redundant and thus more effective. The holding device that holds the second sealing device simplifies the first installation of the brake as well as the replacement of brake parts. The third sealing device further increases redundancy and thus the effectiveness of the sealing system. The holding device adds two functions: it holds the second sealing device and it interacts with the third sealing device to seal the annular space since the third sealing device bears against the holding device. Therefore the holding device is of special importance for the sealing system.
According to the invention, the through opening is a functional opening. In other words, at least one brake element that contributes to the functioning of the brake extends through the through opening. It can be the pressure collar of an adjusting nut and/or a pressure piston that may also be designed as a pressure spindle.
According to the invention, the device that extends through the through opening comprises a pressure collar and/or an adjusting spindle.
In a preferred embodiment of the invention, the holding device has a sleeve design. This results in particularly easy handling during first installation and part replacement.
The second sealing device preferably has a T-shaped cross section. The part that corresponds to the vertical bar of the “T” is preferably used for particularly reliable sealing of annular space while the transverse bar is used to fasten the sealing device within the brake.
According to the invention, the holding device also preferably couples the second sealing device in circumferential and/or axial direction of the brake with the device that extends through the through opening. It thus turns with the pressure collar, for example, when the brake is adjusted.
According to another preferred embodiment of the invention, the device that extends through the through opening and/or the adjusting device comprise(s) a male thread that cuts into the second sealing device at the transition from a first to a second operating state.
For example, the male thread will cut into the second sealing device on first contact, that is, at the transition from new to another operating state. This causes the sealing device to come to rest against the flanks of the male thread. The same effect occurs if a multi-start thread is used. This makes automated assembly processes simpler or makes them work at all.
According to the invention, the portion of the sealing device that engages in the male thread is designed and/or formed in such a way that it will not twist as a result of relative movement of the male thread.
Appropriate dimensioning (radial length) of the relevant part (vertical bar of the “T”) will particularly contribute to this.
The holding device, the second sealing device, and at least one part of the device that extends through the through opening, especially the pressure collar, make up a prefabricated module according to yet another preferred embodiment of the invention. This simplifies first installation of the brake and part replacement.
It is further preferred that the module is prefabricated by compression molding. This also makes the manufacturing and/or replacement process easier.
According to the invention, it is further preferred to provide a grease reservoir that is delimited by the second sealing device. Other parts that can form the perimeter of the grease reservoir include a pressure block and/or a pressure spindle with a male thread. This can prevent friction coefficient variations for parts that glide on one another.
According to the invention, the third sealing device flatly rests against a portion of the inner wall of the through opening. This improves the reliability of the seal.
According to the invention, the third sealing device preferably comprises a portion protruding radially outwards beyond the inner wall of the through opening. This fastens it in axial direction of the brake.
The third sealing device of the invention is also preferably annular. This makes it fit to the annular space.
According to the invention, an inner diameter of the third sealing device is smaller in idle state than an outer diameter of the holding device.
in the assembled state, the third sealing device will therefore come to rest against the outer shell of the holding device, which increases the sealing effect.
According to the invention, the third sealing device preferably comprises a sealing lip stretching radially inwards. The main purpose of this sealing lip is to rest against the outer shell of the holding device for effective sealing of the annular space.
According to the invention, it is further preferred that the third sealing device is at least in some sections elastic. The elastic restoring force can be used for better sealing.
According to the invention, the third sealing device can comprise a reinforcement, especially in the form of an embedded metal ring. It is used in particular for protective and stabilizing purposes and thus also supports the holding and sealing function on the outer surface of the through opening.
It is preferred according to the invention that the second sealing device, the third sealing device, and/or the holding device have a rotationally symmetric design. This means that they do not have to be brought into a specific rotational position during assembly.
The surface area of the holding device against which the third sealing device rests has a smooth finish that promotes the sealing effect. In particular, the holding device is made of metal. It takes much less effort to give the holding device a particularly smooth surface than, for example, to give the pressure collar an according design. The smooth surface is particularly advantageous in embodiments in which the third sealing device is moved relative to the surface it interacts with during brake operation, i.e. the holding device.
In the disc brake according to the invention, the brake application shaft is advantageously supported by a pressure block on its brake application end.
Furthermore, the adjusting device advantageously comprises an adjusting nut and an adjusting spindle.
The through opening can be provided on the main body of the brake caliper or on the lid of the brake caliper.
It is preferred that the lid and the third sealing device form a prefabricated module. When it is installed, the third sealing device moves onto the holding device, which makes installation even simpler.
Finally, the invention preferably provides a pneumatically and/or electromechanically actuable commercial vehicle disc brake having a brake disc, a brake caliper, a brake application shaft which can be actuated by means of a pivoting lever and lies transversely with respect to a rotational axis of the brake disc, an adjusting device which is arranged at least partially within an inner space of the brake caliper, a first sealing device for sealing an annular space which is delimited by the inner wall of a through opening of the brake caliper and a device which extends through the through opening, a holding device that holds a second sealing device for sealing the annular space at least partially, and a third sealing device that bears against the holding device for sealing the annular space at least partially, characterized in that the device that extends through the through opening comprises a pressure collar of an adjusting nut and in that the holding device, the second sealing device, and the pressure collar form a prefabricated module.